Fresh, ripe plums pair incredibly well with the rich flavor of vanilla.
Put a large pot of water on the hob to boil, and prepare a separate large bowl or pot with ice water.
Wash the plums and cut a small x on the bottom of the skin.
Flash boil the plums for about 30 seconds to loosen the skins and then shock them in the ice bath.
If the plums are ripe, the skins should now peel off easily with your fingers.
Cut up the plum flesh into a blender, discarding the stones.
Run the blender on purée for a couple minutes until it's super smooth.
In a large bowl, whisk together sugar and egg until it's thick and creamy.
Cut an incision along one side of the vanilla bean and scrape the tiny seeds into the sugar and egg mix. Keep whisking another minute or so.
Pour in a cup and a half of heavy cream and mix well.
Pour in the plum purée and mix well.
Mix in a cup of milk.
Transfer to your freezer and crank!